In many power applications, such as in HVDC systems, a DC reactor is connected in series with a converter to reduce the harmonic currents on the DC or AC side of the converter or to reduce the risk of commutation failures by limiting the rate of rise of the DC line current at transient disturbances in the AC or DC systems. The converter reactor is surrounded by a shield to avoid inductive heating of the walls of the building in which the reactor is provided and to decrease the magnetic coupling between the three phases. The shields may also contribute to the RI shielding.
Different kinds of shield designs have been used. One example is solid aluminium plates. However, this solution has the drawback of the risk for sound emission. Another drawback is difficult construction on site due to welding operations when the plates are joined to surround the reactor.
Some prior art solutions involve water cooling of the shield. However, this leads to an expensive and complex arrangement.